The XML structure has a Catalog XML group and a Book XML group. The Catalog XML group contains the <Book> element. The Book XML group contains the <Author> and <Title> elements.
When you add an XML file to a single-table constraint or table pair, you select an XML group. The child elements of the XML group appear as table columns in the single-table constraint or table pair. For example, you add the Book XML group to a single-table constraint. Author and Title appear as columns in the single-table constraint. You can create single-table constraint tests on these columns.
An XML group in Data Validation Option is equivalent to an XML view in PowerCenter.